JP2010131258A - Body motion detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a body motion detecting device capable of measuring the total pressure applied to an optionally selected area and the pressure in each of segmented places of the place of the optionally selected area at the same time so that the pressure distribution can be measured. <P>SOLUTION: The body motion detecting device for detecting motions of respective regions of the body of a subject while sleeping includes: a pressure sensing means disposed in the bedclothes of the subject and having at least one conductive elastomer sheet whose resistance changes according to the pressure received in a region of a prescribed shape as a pressure sensor; a resistance detecting means for detecting the change of resistance of the conductive elastomer sheet by converting the change of the resistance into the voltage or currents; a resistance/pressure converting means for converting the detected resistance into the pressure; and a pressure distribution computing means for computing the pressure distribution from the converted pressure value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a body movement detection device that detects movement of each part of a subject's body at bedtime. The present invention is characterized in that pressure information, which is basic data for detecting body movement, is detected using a conductive elastomer sheet as a pressure-sensitive sensor.

  As prior art documents using a conductive elastomer sheet, there are Patent Document 1 and Patent Document 2. The apparatus disclosed in Patent Document 1 is a measurement vertical needle type probe, a control method thereof, and a measurement vertical needle type probe apparatus, and the problem to be solved is to obtain stable measurement data and enable accurate measurement. To provide a new vertical probe for measurement

  The structure as a solving means is that a probe needle, a cylinder part that supports the probe needle, a support part that supports the cylinder part so as to move up and down, and a resistance value that is pressed according to the amount of movement of the cylinder part. The pressure-sensitive conductive rubber is changed and a pressing portion provided in the cylinder portion to press the pressure-sensitive conductive rubber.

  The apparatus disclosed in Patent Document 2 is a ground contact area measuring apparatus, and a problem to be solved is to provide a ground contact area measuring apparatus that has a very simple configuration and contributes to a reduction in processing load of the system.

  The structure as a solution includes a planar bottom electrode, a planar top electrode, a low conductivity member uniformly disposed between both electrodes and having a predetermined conductivity and shape, and the low conductivity member And a grounding area measuring sensor comprising a blocking member that cuts off the contact between the low-conductivity member and the upper electrode, and when an object is placed on the grounding area measuring sensor, When the object is removed, the blocking member or the like located in the position is elastically deformed by the load of the object to allow contact between the low conductive member and the upper electrode. The point is that the low-conductivity member and the upper electrode are disconnected from each other by being restored.

JP 2000-046865 A JP 2000-22003 A

The apparatus described in Patent Document 1 has the following problems.
(1) Pressure-sensitive conductive rubber is used as a sensor whose resistance value changes according to pressure. The pressure-sensitive conductive rubber is not suitable for low pressure because the resistance value hardly changes when the applied pressure is low. In general, the price is high.
(2) When pressure is applied to the pressure-sensitive conductive rubber, the increase in volume resistivity that occurs as a result of volume reduction must be canceled out, and the volume resistivity decrease beyond that must occur. I must. For this purpose, the pressure-sensitive conductive rubber must contain a large amount of a conductive material such as metal or carbon black.
(3) Since it is an integrated device and the mounting method is fixed, it cannot be used as a general-purpose measuring device.
(4) Although the total value of the pressure applied to the whole pressure-sensitive conductive rubber can be measured, the pressure value at an arbitrary place cannot be measured. That is, the pressure distribution cannot be measured.

The apparatus described in Patent Document 2 has the following problems.
(1) The output of each detection point is generally only binary of on / off. Continuous detection is not possible. It is specialized for measuring the contact area and is not suitable for measuring body pressure distribution.
(2) Although the installation area can be measured, the installation location cannot be specified.
(3) The number of parts is large. The sensor which consists of a low electroconductive member and a blocking member is required for the number of detection points.

The present invention has been made to solve the above-described problems,
(1) The total value of the pressure applied to an arbitrary area can be measured, and at the same time, the pressure value at each location obtained by subdividing the location of the arbitrary area can be measured, so that the pressure distribution can be measured.
(2) Not only the pressure measurement, but also the volume measurement of the part where the pressurized object including the subject's body bites into the elastomer sheet, and the area measurement of the part where the pressurized object including the subject's body contacts the elastomer sheet are possible To.
(3) Make the wearing pressure as thin and light as possible.
(4) To be robust so that it does not break even if it is stepped on by the subject's feet on the bed, so that it can withstand repeated daily use.
(5) It is flexible and improves sleeping comfort.
(6) Increase durability against repeated bending back.
(7) Use a simple configuration.
(8) Reduce costs so that they can be purchased and used in ordinary households.
(9) A pressure correction can be made on the basis of the compression history so far with respect to a change in resistance value due to compression set of elastomer, reduction in impact resilience, and deterioration (aging).
The purpose is that.

In order to achieve such a subject, the present invention has the following configuration.
In the body motion detection device that detects the movement of each part of the subject's body at bedtime,
Pressure sensor means arranged on the bedding of the subject and having at least one conductive elastomer sheet whose resistance changes depending on the pressure received in a region of a predetermined shape as a pressure sensor;
Resistance detection means for detecting a change in resistance of the conductive elastomer sheet by converting it into a voltage or current; and
Resistance / pressure converting means for converting the detected resistance into pressure;
Pressure distribution calculating means for calculating a pressure distribution from the converted pressure value;
It is characterized by providing.

  The pressure sensor means is divided into a plurality of conductive elastomer sheets having a predetermined shape with a predetermined interval, and all or part of one surface of two adjacent conductive elastomer sheets is highly conductive. Connect with an elastomer sheet or conductor, and for the next adjacent conductive elastomer sheet, connect all or part of the opposite surface to the previous conductive elastomer sheet with a highly conductive elastomer sheet or conductor. And after that, it is good also as a structure which connected all the conductive elastomer sheets by changing the side of the connection surface with an adjacent conductive elastomer sheet alternately.

  The conductive elastomer sheet is inserted or filled with an insulating elastomer having a higher rebound resilience than itself, and the restoring force of the conductive elastomer is enhanced by the resilience of the high resilience insulating elastomer. Also good.

  The surface of the conductive elastomer sheet may be uneven, and the distance between the input and output terminals may be increased to increase the surface resistance.

  In the conductive elastomer sheet, at least one branch input / output terminal is formed in the middle between the input / output terminals at both ends, and the resistance value between one or both of the branch input / output terminals and the input / output terminals at both ends is small. It may be detected.

  The branch input / output terminal is formed by extending the same elastomer material as the conductive elastomer sheet from the take-out port, and in order to reduce the electrical influence on the conductive elastomer sheet at the take-out port portion, The shape may be made thinner or thinner than the surrounding part to increase the resistance.

  The input / output terminals at both ends of the conductive elastomer sheet or at least one branch input / output terminal formed between the input / output terminals may be injected or coated with a conductive resin at the terminal portion.

  Among the input / output terminals at both ends of the conductive elastomer sheet and a plurality of branch input / output terminals arranged at a predetermined interval between the input / output terminals, either one or both of the input / output terminals at both ends Is fixed as one input / output terminal (measurement terminal) for measuring the voltage or current between the input / output terminals, and the other input / output terminal as the other input / output terminal (reference terminal). By measuring the voltage or current between the reference terminal, the pressure applied to the region between the measurement terminal and the reference terminal may be detected.

  A pressure sensor means in which a plurality of the pressure-sensitive sensor means arranged in the same direction and a plurality of pressure-sensitive sensor means arranged in a direction perpendicular to the line are superposed; Also good.

  The conductive elastomer sheet has a characteristic that does not reach the minimum sheet thickness in the applied pressure range, and the volume of the pressurized object including the subject's body from the output of the resistance detection means bites into the conductive elastomer sheet. You may have a biting volume detection means to detect.

  An area of a portion where a pressurized object including the subject's body comes into contact with the conductive elastomer sheet from an output of the resistance detection means, the conductive elastomer sheet having a characteristic of reaching a minimum sheet thickness in a pressure range to be applied You may have a contact area detection means to detect.

  A resistance value correcting unit that corrects a change in resistance value due to compression set, reduction in impact resilience, or deterioration of the conductive elastomer according to a compression history or a change history of resistance value may be provided.

  A resistance value correcting unit that corrects a decrease in the resistance value caused by the pressure applied to the conductive elastomer according to the history of changes in the resistance value so far may be provided.

  The pressure sensor means may comprise an elastomer lead, resistance, variable resistance, capacitor or coil.

According to the configuration of the present invention, the following effects can be expected.
(1) Since the total value of pressure applied to an arbitrary area can be measured, the pressure value at each location obtained by subdividing the location of the arbitrary area can also be measured, so that the pressure distribution can be measured.
(2) Not only the measurement of pressure, but also the measurement of the volume where the pressurized object including the subject's body bites into the elastomer sheet, and the area measurement of the part where the pressurized object including the subject's body contacts the elastomer sheet are possible. .
(3) By selecting an elastomer material, the thickness of the sheet can be reduced, and at the same time, the weight can be reduced accordingly. Moreover, there is no electrode in the wearing pressure measurement target area. Therefore, it is suitable for the measurement of wearing pressure.
(4) It has robustness that does not break even if it is stepped on by the subject's feet on the bed, and can withstand repeated daily use.
(5) Both the conductive elastomer and the electrode are flexible and comfortable to sleep.
(6) Durability against repeated bending back is great.
(7) The number of parts is small because of the simple structure in which the electrode is attached to the conductive elastomer.
(8) Since a foamed product can be used as the conductive elastomer, the cost is low.
(9) The change in resistance value due to the compression set, the rebound resilience, and the deterioration (aging) of the elastomer can be corrected based on the compression history so far.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Prior to the description with reference to the drawings, the physical properties of the conductive elastomer, the measurement principle of the present invention, the measurement method, and the component parts, which are the basis of the present invention, will be described.

  The elastomer (elastic polymer) forming the conductive elastomer sheet used in the present invention is divided into two types, rubber and thermoplastic elastomer. The pressure-sensitive resistor, the volume specific resistance, and the surface specific resistance representing the characteristics of the conductive elastomer, that is, the conductive rubber and the conductive thermoplastic elastomer will be described.

(1) Pressure-sensitive resistor: A resistor whose volume resistivity changes due to the influence of external pressure. Most of them are made of an elastomer, and in many cases, when an external pressure is applied, the volume resistivity decreases and the electrical conductivity is exhibited from semi-electrical conductivity.

(2) Volume resistivity: When a current flows inside an object, it is a resistance mainly determined by the type of the object. It is defined by the resistance between opposing faces of the cube with the unit length as the side. cm.

(3) Surface resistivity: When a current flows on the surface of an object, it is a resistance mainly determined by the type of object and the surface state, and is defined by the resistance between opposing sides of a square whose side is a unit length. The unit is Ω.
The elastomer in the present invention is an elastic polymer substance and includes rubber and a thermoplastic elastomer.

1) Physical properties of conductive elastomers Conductive elastomers are mainly composed of two materials: an insulating elastomer material and conductive particles such as metal and carbon. The conductive elastomer is almost completely contained in the insulating elastomer material. Molded in an evenly dispersed state.

  When no pressure is applied, the conductive particles do not contact each other (the state where no conductive path is formed), and both the volume resistance and the surface resistance exhibit very high electrical resistance values. Since the particles gradually come into contact with each other and a conductive path is formed, the electric resistance value is lowered. Further, when the pressure is reduced and no pressure is applied, the conductive particles return to the non-contact state again by the restoring force due to the elasticity of the elastomer, and the electric resistance value becomes very high.

2) Measurement principle When pressure is applied to the conductive elastomer, the resistance value decreases as follows.
Pressure is applied to the seat surface. → The point where the pressure on the sheet surface is applied is compressed and the thickness is reduced. → Conductivity increases as individual conductive particles approach or come into contact with each other.
→ The resistance value (volume resistivity value) decreases.

3) Measurement method (1) Method using voltage detection terminal Prepare an input / output terminal at the position where you want to detect the voltage. A voltage is applied via a resistor between a plurality of fixed input / output terminals, and the voltage between the potential reference terminal and the input / output terminal whose voltage is to be detected is measured. Measure the voltage between the required voltage detection terminal and the potential reference terminal. Alternatively, a method may be used in which a constant current is supplied between the input and output terminals to measure the voltage between the terminals.

(2) Method of switching voltage application terminals A voltage is applied between a plurality of input / output terminals via a resistor, and the potential reference terminal is switched to measure the voltage between the input / output terminals to be detected.

(3) Method for calculating each element of the pressure distribution matrix The region in which the pressure distribution is to be measured is divided into a row direction and a column direction. The pressure value of each element constituting the matrix is obtained by calculating from the pressure measurement value of each row sensor means in the row direction and the pressure measurement value of each column sensor means in the column direction.

  As an example of the realization method, there is a method of measuring with a structure in which row sensor means and column sensor means are overlapped. A thin insulating elastomer sheet is inserted between the plurality of row sensor means columns and the plurality of column sensor means columns to prevent conduction between the row sensor means and the column sensor means.

  The calculation method of each element of the pressure distribution matrix can be calculated in the case of a simple pressure distribution, but may be difficult to calculate in the case of a complicated pressure distribution. This is the case when equations are insufficient to determine each element of the pressure distribution matrix.

  In order to add these equations, branch input / output terminals for voltage detection are provided at portions other than both ends of the row sensor means or the column sensor means. By detecting the voltages at these branch input / output terminals, the row sensor means or the column sensor means can be subdivided, and the voltages in the subdivided areas can be detected. It is possible to calculate the pressure value of each element of the pressure distribution matrix by disposing the necessary number of branch input / output terminals and eliminating the insufficient equations.

The added branch input / output terminal extends to the end of the conductive elastomer sheet and is used as a voltage detection terminal.
By calculating the resistance value on both sides of the added branch input / output terminal as a boundary, the pressure applied to the both sides can be obtained.

4) Electrical circuit component (1) Material and manufacturing method The lead wire is manufactured from a highly conductive elastomer having high conductivity. The resistor is made of a semiconductive to highly conductive elastomer. When the same material is used, the resistance value can be changed by changing its shape. The variable resistor is manufactured using a conductive elastomer.

  The capacitor is manufactured by inserting a dielectric elastomer between two highly conductive elastomer sheet surfaces. The coil is manufactured by winding a thin and thin highly conductive elastomer with an insulating elastomer pasted into a cylindrical shape.

  The reason why the insulating elastomer is attached to the highly conductive elastomer is to prevent conduction between the windings due to the highly conductive elastomer. The insulating material may be coated on the peripheral surface of the highly conductive elastomer without attaching the insulating elastomer.

(2) Resistance value fluctuation range of variable resistance The resistance of the elastomer is a parallel connection of a volume specific resistance which is a resistance to a current flowing inside the object and a surface specific resistance which is a resistance to a current flowing through the surface of the object. Therefore, in order to increase the resistance value fluctuation range with respect to the entire resistance value of the variable resistor, the resistance value due to volume resistivity or surface resistivity when pressure is applied is reduced as much as possible, or when no pressure is applied. To increase the volume resistivity or surface resistivity as much as possible.

a. Method of reducing the resistance value at the time of pressurization When the pressure is applied, the thickness of the conductive elastomer sheet is reduced, and the individual conductive particles in the conductive elastomer sheet approach each other or come into contact with each other. To increase the volume resistivity and reduce the volume resistivity.

  At the same time, not only electrically but also structurally, the length in the thickness direction is shortened by reducing the thickness, and the resistance value due to volume resistivity and surface resistivity is reduced. The input / output terminal is electrically connected to one surface of the sheet to be pressed and the opposite surface so that the resistance value between both surfaces is measured.

b. Increasing resistance when no pressure is applied Increase resistance as much as possible so that resistance does not change even when pressure is applied. There is a surface whose surface area does not change even when pressure is applied depending on the pressing direction, so that the surface is not flat but uneven, increasing the surface area and increasing the distance on the surface between the input and output terminals, Increase the resistance value due to surface resistivity. The input / output terminals are attached to both ends of the pressed sheet so that the resistance value between the both ends of the sheet is measured.

5) Input / output terminals (1) Types of input / output terminals (A) Input / output terminals when the influence on the electric circuit needs to be considered Input / output terminals used when the influence on the electric circuit must be considered .
The input / output terminal is integrated with the electric circuit component, and is made by extending the same elastomer material as the electric circuit component from the outlet.

  In order to reduce the influence on the electric flow on the electric circuit component side at the take-out port portion, the shape of the take-out portion is made as thin or thin as possible to increase the resistance. By injecting or coating a conductive resin on the terminal portion of the extended portion, electrical connection with the electrode is improved.

As an example of a concrete realization method,
a. Filled conductive silicon compound is injected into the end portion of the extension.
b. A conductive adhesive is applied to the end portion of the extended portion.
There are methods.
In the case of a voltage application terminal, the size of the elastomer material in the extension portion ahead of the take-out port portion is made as wide and thick as possible to reduce loss resistance caused by passing current.

(B) Input / output terminal when the influence on the electric circuit is not required It is an input / output terminal used when the influence on the electric circuit need not be considered.
The input / output terminal is integrated with the electric circuit component, and is made by extending the same elastomer material as the electric circuit component.

  By injecting or coating a conductive resin on the terminal portion of the extended portion, the volume specific resistance or surface specific resistance is reduced, and conduction with the electrode is improved. By injecting the conductive resin, the volume resistivity can be reduced. The surface resistivity can be reduced by coating the conductive resin.

As an example of a concrete realization method,
a. Filled conductive silicon compound is injected into the end portion of the extension.
b. A conductive adhesive is applied to the end portion of the extended portion.
There are methods.
In the case of a voltage application terminal, the size of the elastomer material of the extension portion is as wide and thick as possible to reduce the loss resistance caused by passing a current.

(2) Peripheral arrangement of input / output terminals The electrode parts of the input / output terminals are arranged outside the pressure measurement target area. That is, the electrode portion of the input / output terminal is disposed in the peripheral portion of the pressure sensitive sensor means.
Therefore, since there is no electrode in the part which contacts a test subject's body, sleeping comfort becomes good.
In addition, since the movement of the subject's body is not directly transmitted to the electrode part, the mechanical impact on the electrode part is reduced, and it becomes possible to withstand long-term use.

6) Insertion and filling of insulating elastomer Inserting insulating elastomer into the space between electrical circuit parts and input / output terminal parts made of elastomer material and between the pressure sensor means and pressure sensor means Alternatively, by filling and making the thickness, hardness or rebound resilience of the entire sensor means uniform, the contact portion with each part of the body of the subject becomes flat without unevenness, and the rebound resilience and hardness are uniform, so that the sleeping comfort is good.
Further, even when a large force is applied in the tangential direction, no displacement occurs and the sensor is not destroyed.

7) Method of fixing elastomer in pressure sensor means In order to prevent displacement of the elastomer used in the pressure sensor means, it is necessary to fix these elastomers to a sheet made of a material having insulating properties.

As a method of fixing the elastomer used in the pressure sensor means to a sheet made of an insulating material,
a. A method of applying with an insulating adhesive or an insulating adhesive sheet b. There is a method of bonding using an insulating surface fastener.

  When pasting with an adhesive or an adhesive sheet, an insulating adhesive or adhesive sheet is used so as not to affect the surface resistance of the elastomer itself. In the case of bonding using a hook-and-loop fastener, an insulating hook-and-loop fastener is used so as not to affect the surface resistance of the elastomer itself.

  The hook of the hook-and-loop fastener is attached to one of the elastomer or the sheet, and the loop of the hook-and-loop fastener is attached to the other, and the elastomer is fixed to the sheet by engaging the hook and the loop. The hook-and-loop fastener is detachable and can be used repeatedly, which is convenient when replacing the elastomer.

8) Covering method of the pressure sensor means Since the pressure sensor means comes into contact with a pressurized object including a human body, it is necessary to cover the surface of the pressure sensor means with an object made of an electrically insulating material. Moreover, it is necessary to cover with the thing made from the flame-retardant material in order to make it hard to burn.

  Including the pressure sensor means and the electrodes attached to the pressure sensor means, it is covered with a bag made of an insulating or flame retardant material. By doing so, electrical insulation can be maintained, and at the same time, a non-flammable material can be adopted as an elastomer material in the pressure sensor means, and the degree of freedom in material selection is widened. Furthermore, all the pressure sensitive sensor means in the pressure sensor means can be kept at the same temperature and humidity, and each sensor can be used under the same environmental conditions.

9) Electrode A conductive adhesive tape, a metal foil tape, or a copper tape that can be flexibly deformed is used as the electrode.
Pressure sensor means by attaching a conductive adhesive tape, metal foil tape or copper tape to the surface of the electrode mounting part of the input / output terminal into which conductive resin has been injected or applied, or winding it around the electrode mounting part Send and receive electrical signals to and from.

The configuration of the present invention will be described below with reference to the drawings.
FIG. 1 is a functional block diagram showing an embodiment of a body motion detection device to which the present invention is applied. The body motion detection device is composed of pressure sensor means 100, pressure detection means 200, and pressure distribution calculation means 300.

  The pressure sensor means 100 is composed of four pressure-sensitive sensor means 101 to 104 made of a conductive elastomer sheet, and the longitudinal direction of the conductive elastomer sheet is in a predetermined region in the longitudinal direction of the bedding on which the subject sleeps. Has been placed.

  If each of the pressure sensor means 101 to 104 shows the pressure sensor means 101 as a representative, there are electrode mounting portions 101a at both ends, and electrodes 101b are attached thereto, and each is connected via a resistor R. Voltage E is applied.

  The same electrode 101b is attached to the bottom surface of the electrode mounting portion at the right end of each pressure-sensitive sensor means, and is kept at the same potential. Individual electrodes are attached to the bottom surface of the electrode mounting portion at the left end of each pressure-sensitive sensor means.

  The pressure detection unit 200 includes a resistance detection unit 201 and a resistance / pressure conversion unit 202. The resistance detection means 201 receives voltages V1 to V4 between both ends of each of the pressure sensor means 101 to 104, and detects resistance values R1 to R4 of the pressure sensor means 101 to 104 from those voltages to detect resistance. / Output to pressure conversion means 202.

  The resistance / pressure conversion means 202 converts the input resistance values R1 to R4 into pressure values P1 to P4 and outputs them to the pressure distribution calculation means 300. Those pressure values are the total values of the pressure values applied between the both ends of each pressure-sensitive sensor means 101-104.

  Based on the input pressure values P1 to P4, the pressure distribution calculation means 300 calculates and outputs the body pressure distribution of the subject in the region formed by the pressure sensor means 101 to 104 by a predetermined algorithm.

  FIG. 2 is a cross-sectional view and an equivalent circuit showing an embodiment of the pressure-sensitive sensor means 101-104. The pressure-sensitive sensor means 101 to 104 are equivalent to variable resistors of electric circuit parts. In this embodiment, for the four conductive elastomer sheets A, B, C, and D, the upper surfaces of A and B, the lower surfaces of B and C, and the upper surfaces of C and D A variable resistor having a structure connected by a conductor is shown in FIG. As the conductor, a conductive adhesive tape, a metal foil tape, a copper tape, or the like that can be flexibly deformed is suitable.

  In FIG. 2 (b), insulating elastomers E, F, G, H and I having higher resilience than A, B, C and D are attached to both sides of the conductive elastomer sheets A, B, C and D. An embodiment in which the impact resilience force is increased is shown.

  The conductive elastomer sheets A, B, C, and D used as pressure-sensitive sensor means are subjected to repeated pressurization, so that compression set, reduction in rebound resilience, deterioration (aging), etc. proceed. By attaching the insulating elastomers E, F, G, H, and I, the progress can be delayed.

  When the pressure is removed, the resilience of the high resilience insulating elastomers E, F, G, H, I is in the direction of stretching the conductive elastomer sheets A, B, C, D, that is, the resilience Because it works in the direction of strengthening.

  The equivalent circuit of the variable resistor shown in FIGS. 2A and 2B is expressed as shown in FIG. The variable resistances RAV, RBV, RCV, and RDV are resistances due to the volume resistivity of the conductive elastomer sheets A, B, C, and D. The variable resistances RAS, RBS, RCS, and RDS are the conductive elastomer sheets A, B, Resistance due to surface resistivity of C and D. Note that the resistance of the highly conductive elastomer sheets or conductors on the upper and lower surfaces is small and neglected.

  When pressure is applied to the conductive elastomer sheets A, B, C, and D as shown in the figure, the thickness of the conductive elastomer sheets A, B, C, and D is reduced. As the conductive particles approach or come into contact with each other, the conductivity increases and the volume resistivity decreases.

  Also, structurally, the length in the vertical direction is shortened as the thickness is reduced, and the resistance value due to the volume resistivity is reduced. In the case of this embodiment, since the length in the vertical direction is shortened as the thickness is reduced, the resistance value due to the surface specific resistance is also reduced.

  FIG. 3 is a sectional view and an equivalent circuit showing another embodiment of the pressure-sensitive sensor means. The embodiment is shown as a variable resistance of an electric circuit component in which the conductive elastomer sheet itself is modified.

FIGS. 3A and 3B show examples in which the shape of the upper and lower surfaces of the conductive elastomer sheet is triangular, and the surface distance between the input and output terminals is increased. Both are shown in cross-sectional side views. In FIG. 3A, the triangular wave on the upper surface protrudes upward and the triangular wave on the lower surface protrudes downward.
In FIG. 3B, the triangular wave on the upper surface and the triangular wave on the lower surface are in the same direction.

  FIG. 3 (c) shows an equivalent circuit of FIGS. 3 (a) and 3 (b). This equivalent circuit is approximated by a parallel circuit of a variable resistance Rv based on a volume specific resistance and a variable resistance Rs based on a surface specific resistance.

  As the pressure-sensitive sensor means, a variable resistor having as large a resistance change as possible with respect to pressure fluctuation is required. When pressure is applied, the resistance value decreases. However, the thickness of the conductive elastomer sheet decreases, and the conductivity increases as individual conductive particles in the conductive elastomer sheet approach or contact each other. Because.

  On the other hand, even if the thickness of the conductive elastomer sheet is reduced, the surface distance between the input and output terminals is not shortened, so that the resistance value due to the surface specific resistance does not change. In other words, even if the pressure fluctuates, it does not contribute to the change of the resistance value.

  For this reason, the resistance due to the surface specific resistance is a component as a parallel resistance, and therefore the resistance value due to the surface specific resistance should be increased as much as possible. Therefore, since the resistance value due to the surface specific resistance is proportional to the distance, the distance on the surface between the input / output terminals is made as long as possible.

  In the embodiment of FIG. 3A and FIG. 3B, the surface has a triangular wave shape, and the distance between the input and output terminals on the surface is increased. The shape of the surface is arbitrary, and besides the triangular wave shape, there are many shapes such as an arc shape and a trapezoidal shape, and the surface may be uneven.

FIG. 4 is a functional block diagram showing another embodiment of the body motion detection device to which the present invention is applied.
Differences from the embodiment of FIG. 1 will be described. The pressure sensor means 100 is composed of three pressure-sensitive sensor means 101 to 103 made of a conductive elastomer sheet.

  Branch input / output terminals 101c, 102c, and 103c are formed at the center of the pressure sensitive sensor means 101, 102, and 103, and are used as voltage detection terminals at the center. The resistance detection means 201 is input with voltages V11, V12, V13 between the central part and the right end of each pressure-sensitive sensor means and voltages V21, V22, V23 between both ends, and resistance values R11, R12, R13, R21, R22, and R23 are detected.

  The resistance / pressure converting means 202 converts the input resistance value into pressure values P11, P12, P13, P21, P22, and P23 and outputs them. These pressure values are the total values of the pressures applied between the central part and the right end and between both ends of each pressure-sensitive sensor means.

  These pressure values are input to the pressure distribution calculating means 300, and the body pressure distribution of the subject in the region formed by the pressure sensor means 101 to 103 is calculated and output by a predetermined algorithm. Compared with the embodiment of FIG. 1, finer pressure distribution information can be obtained in the longitudinal direction of the pressure-sensitive sensor means.

  FIG. 5 is a plan view and an equivalent circuit showing an embodiment of a pressure-sensitive sensor means having a branch input / output terminal. FIG. 5A shows a plan view of a pressure-sensitive sensor means composed of a variable resistor made of a conductive elastomer sheet and input / output terminals arranged in the variable resistor. An equivalent circuit of the variable resistor is shown in FIG.

  Electrodes are attached to the input / output terminals at both ends of the variable resistor and the three branch input / output terminals attached in the middle of the variable resistor. The voltages detected at the branch input / output terminals b, c, and d attached in the middle of the variable resistor when the voltage V4 is applied between the points a and e of the variable resistor are indicated by V3, V2, and V1, respectively. .

  The resistance value between the variable resistors a to e is a value obtained by adding in series the respective resistance values of the regions a to b, b to c, c to d, and d to e, which are subdivided regions. Further, in order to reduce the electrical influence on the conductive elastomer sheet at the take-out port portion of the branch input / output terminal, the shape of the take-out portion is made thinner or thinner than the surrounding portion to increase the resistance.

  FIG. 6 is a perspective view and an equivalent circuit showing another embodiment of the pressure-sensitive sensor means having a branch input / output terminal. FIG. 6A shows an embodiment in which the branch input / output terminals are extended to the periphery of the input / output terminals at both ends of the pressure-sensitive sensor means. The equivalent circuit is shown in FIG.

  In this embodiment, current may flow through all six input / output terminals including the branch input / output terminals. Therefore, in order to reduce resistance loss at the input / output terminals, the resistance value must be made as small as possible. Don't be. Therefore, a highly conductive elastomer with high conductivity is used as the material.

  FIG. 7 is a plan view and an equivalent circuit showing still another embodiment of the pressure-sensitive sensor means having a branch input / output terminal. The pressure-sensitive sensor means shown in FIG. 7A is a variable resistor made of a conductive elastomer sheet, and includes two input / output terminals a and f and four branch input / output terminals b, c, d, and e. Have

  Connected between the branch input / output terminals b, c, d, e and the power supplies E1 and E2 are switches SWb to SWe that are selectively opened and closed. In this embodiment, only the switch SWd is on. The equivalent circuit is shown in FIG.

  Voltage is applied to the input / output terminals a and f at both ends of the variable resistor, the input / output terminals a and f are measurement terminals, and the branch input / output terminals b, c, d, and e are Reference terminal. By fixing the measurement terminal to both ends of the variable resistor and selectively switching the reference terminal with a switch, it is possible to measure the voltages on both sides of the reference terminal.

  FIG. 8 is a perspective view showing an embodiment in which a plurality of pressure-sensitive sensor means are stacked in the row direction and the column direction. FIG. 8A shows a configuration in which 11 row sensor means are arranged in parallel. FIG. 8B shows a configuration in which six column sensor means are arranged in parallel.

  FIG. 8C shows a structure in which 11 row sensor means and 6 column sensor means are overlapped. Such a matrix configuration makes it possible to estimate and calculate the pressure at the intersection, and to calculate the body pressure distribution of the subject in the region formed by the pressure-sensitive sensor means with high accuracy.

  FIG. 9 is a perspective view showing another embodiment in which a plurality of pressure-sensitive sensor means are stacked in the row direction and the column direction. The difference from FIG. 8 is that the branch input / output terminals extend from the two outlets near the center of the first row sensor means and the sixth row sensor means to the end of the row sensor means. It is in the configuration.

  These branch input / output terminals are terminals for voltage detection, and are used to subdivide the column sensor means and detect voltages in the subdivided regions. In this embodiment, each of the first column sensor means and the sixth column sensor means is subdivided into three regions by two branch input / output terminals. Compared to the configuration of FIG. 8, it is possible to obtain more detailed pressure distribution information.

  FIG. 10 is a functional block diagram showing an embodiment of a body motion detection device having a biting volume detection means. When detecting the biting volume, it is necessary to select a conductive elastomer sheet having a characteristic that does not reach the minimum sheet thickness as the pressure-sensitive sensor means in the pressure range applied by the body movement of the subject.

When the thickness of the sheet decreases according to the pressure, the resistance value (volume specific resistance value) decreases in proportion to the sum of (applied pressure) × (area to which pressure is applied). Therefore,
The sum of (applied pressure) × (area where pressure is applied) 減少 resistance decrease.

  That is, by measuring the resistance value, the sum of (applied pressure) × (area where pressure is applied) can be obtained. Since the thickness of the sheet decreases in accordance with the applied pressure, the decrease in the sheet thickness is proportional to the applied pressure and becomes the decrease in the sheet thickness.

  Therefore, the total sum of (applied pressure) × (area to which pressure is applied) (reduction in sheet thickness) × (total area to which pressure is applied) ∝reduction in resistance value.

The sum of (the reduction in sheet thickness) × (the area where pressure is applied) is equal to the volume reduction of the sheet due to the applied pressure when the area where pressure is applied is subdivided to the limit. That is,
The sum of (sheet thickness reduction) x (area where pressure is applied) ≒ sheet volume reduction.

Therefore,
(Sheet thickness decrease) x (Area where pressure is applied) Total ≒ Sheet volume decrease ∝ Resistance value decrease ... 1)
It becomes.

  That is, the resistance value (volume specific resistance value) decreases in proportion to the volume reduction of the sheet. Therefore, by measuring the resistance value, it is possible to obtain the volume decrease of the sheet. In addition, since the volume reduction of the sheet is equal to the volume of the portion of the pressurized object that includes the subject's body (biting volume), the pressurized object including the subject's body is measured by measuring the resistance value. The volume (biting volume) of the portion biting into the sheet can be determined.

As a method of reducing the thickness of the sheet according to the applied pressure within a wide pressure fluctuation range,
(1) Increase the thickness of the elastomer sheet.
(2) Strengthen the impact resilience of the elastomer sheet material.
(3) Harden the elastomer sheet material.
There are methods.

  10, the configuration of the pressure sensor means 100 is the same as that in FIG. The biting volume detection means 400 includes a resistance detection means 401 and a resistance / biting volume conversion means 402.

  The function of the resistance detection unit 401 is the same as that of the resistance detection unit 201 of FIG. 1, and converts the voltages V1 to V4 into resistance values R1 to R4 and outputs them to the resistance / breaking volume conversion unit 402. The resistance / biting volume conversion means 402 calculates using the input resistance values R1 to R4, converts it into the biting volume V, and outputs it.

In accordance with the measurement principle of the biting volume ∝ resistance decrease in the above formula (1), the biting volume V is
_{V = k V {(R0-} R1) + (R0-R2) + (R0-R3) + (R0-R4)}
= K _V {4R0− (R1 + R2 + R3 + R4)} (2)
Is calculated by Here, k _V proportional coefficient, R0 is the resistance of the pressure sensor means without pressurized.

  FIG. 11 is a functional block diagram showing an embodiment of a body movement detection device having a contact area detection means. When detecting the contact area, it is necessary to select a conductive elastomer sheet having characteristics that reach the minimum sheet thickness in the applied pressure range.

When the thickness of the sheet does not decrease according to the pressure, the amount of decrease in the sheet thickness is constant regardless of the magnitude of the pressure.
(Sheet thickness reduction) x (area where pressure is applied) ≈ (constant coefficient) x (area where pressure is applied) ∝ total sum (area where pressure is applied) 減少 resistance reduction Minutes ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ （3）
It becomes.

  Therefore, the resistance value (volume resistivity value) decreases in proportion to the area where pressure is applied. That is, by measuring the resistance value, the area where pressure is applied can be obtained. Thereby, by measuring the resistance value, it is possible to measure the area of the portion where the pressurized object including the body of the subject contacts the sheet.

As a method for causing the sheet thickness to reach the minimum thickness that is the minimum value of the sheet thickness at the lowest possible pressure within the pressure fluctuation range,
(1) Reduce the thickness of the elastomer sheet.
(2) To weaken the resilience of the elastomer sheet material.
(3) The hardness of the elastomer sheet material is softened.
There are methods.

  11, the configuration of the pressure sensor means 100 is the same as that in FIG. The contact area detection unit 500 includes a resistance detection unit 501 and a resistance / contact area conversion unit 502.

  The function of the resistance detection unit 501 is the same as that of the resistance detection unit 201 of FIG. 1, and converts the voltages V1 to V4 into resistance values R1 to R4 and outputs them to the resistance / contact area conversion unit 502. The resistance / contact area conversion means 502 calculates using the input resistance values R1 to R4, converts it into the contact area S, and outputs it.

According to the measurement principle of the contact area ∝ resistance decrease in the above formula (3), the contact area S is
S = k _S {(R0−R1) + (R0−R2) + (R0−R3) + (R0−R4)}
= K _S {4R0− (R1 + R2 + R3 + R4)} (4)
Is calculated by Here, k _S is a proportional coefficient, and R0 is a resistance value of the pressure-sensitive sensor means when no pressure is applied.

  FIG. 12 is a functional block diagram showing an embodiment of resistance detection means having resistance value correction means. Prior to the description of the drawings, resistance value correction according to the compression history and the change history of the resistance value decrease will be described.

(1) Correction according to compression history The resistance value is corrected according to the compression history with respect to changes in the elastomer resistance value due to compression set, rebound resilience, and deterioration (aging).

  The elastomer used in the pressure-sensitive sensor means undergoes compression set, rebound resilience, deterioration (aging), etc. as pressure is repeatedly applied, and even if the pressure on the elastomer is removed, it returns to its original thickness. Since it disappears, the resistance value becomes small. The decrease in the resistance value is corrected.

Since the decrease in the resistance value is proportional to the amount of compression or the number of compressions up to that point, the resistance value is corrected according to the compression history up to that point.
Correction resistance value = actual resistance value × {1 + h × (value proportional to compression amount or number of compressions)}
h: coefficient or
Correction resistance value = actual resistance value × k / (value proportional to compression amount or number of compressions)
k: As an example of a value proportional to the coefficient compression amount or the compression frequency,
a. Cumulative compression amount (compressed amount integrated over time)
b. A compressed value exceeding a certain value or a cumulative value corresponding to the compressed value c. For example, the sum of compression amount x number of compressions.

(2) Correction according to change history of resistance value decrease This is a method of correcting the resistance value according to the change history of the resistance value decrease itself.
Corrected resistance value = measured resistance value x {1 + m x (value proportional to the decrease in resistance value)}
m: coefficient or
Corrected resistance value = actual resistance value × n / (value proportional to the decrease in resistance value)
n: Coefficient

As an example of the value proportional to the resistance decrease,
a. Cumulative resistance value decrease = A value obtained by time integration of the resistance value decrease b. A resistance value exceeding a certain value or a cumulative value corresponding to the exceeding value c. Maximum resistance decrease = (resistance value when no pressure is applied at the start of use)-(resistance value when no pressure is applied at the present time)
Etc.

  FIG. 12 shows an embodiment in which the resistance value is corrected according to the cumulative resistance value decrease as the resistance value correction method. The pressure detection unit 200 includes a resistance detection unit 201 and a resistance / pressure conversion unit 202.

  The resistance detection unit 201 having a resistance value correction function includes a voltage / resistance conversion unit 201A that converts a voltage input into a resistance value, and a resistance value that corrects the resistance value of the voltage / resistance conversion unit output 201A and outputs a corrected resistance value. It comprises correction means 201B.

  The resistance value correction unit 201B includes a cumulative resistance value decrease calculation unit 201C that integrates the resistance value decrease, and a correction unit 201D that corrects the resistance value based on the cumulative resistance value decrease and outputs a correction resistance value. Composed. The resistance / pressure converting means 202 converts the corrected resistance value input into a pressure value and outputs it.

  FIG. 13 is a perspective view and an equivalent circuit showing a configuration example of a lead wire W, a resistor R, a capacitor F, and a coil L using a conductive elastomer. FIG. 13A shows an example in which a low-pass filter (low-pass filter) is configured using an electric circuit component and an input / output terminal made of elastomer. The equivalent circuit is as shown in FIG.

  The lead wire W is made of a highly conductive elastomer having high conductivity. The resistor R is made of a semiconductive to highly conductive elastomer. When the same material is used, the resistance value can be changed by changing its shape. Although not shown in the figure, the variable resistor is fabricated using a conductive elastomer.

  The capacitor F is manufactured by inserting a dielectric elastomer between two highly conductive elastomer sheet surfaces. The coil L is manufactured by winding a thin, high-conductivity elastomer with an insulating elastomer pasted into a cylindrical shape.

  The reason why the insulating elastomer is attached to the highly conductive elastomer is to prevent conduction between the windings due to the highly conductive elastomer. The insulating material may be coated on the peripheral surface of the highly conductive elastomer without attaching the insulating elastomer.

It is a functional block diagram which shows one Embodiment of the body movement detection apparatus to which this invention is applied. It is sectional drawing and equivalent circuit which show one Embodiment of a pressure-sensitive sensor means. It is sectional drawing and an equivalent circuit which show other embodiment of a pressure-sensitive sensor means. It is a functional block diagram which shows other embodiment of the body movement detection apparatus to which this invention is applied. It is the top view and equivalent circuit which show one Embodiment of the pressure-sensitive sensor means which has a branch input / output terminal. It is the perspective view and equivalent circuit which show other embodiment of the pressure-sensitive sensor means which has a branch input / output terminal. It is the top view and equivalent circuit which show other embodiment of the pressure-sensitive sensor means which has a branch input / output terminal. It is a perspective view which shows embodiment which piled up several pressure sensitive sensor means in the row direction and the column direction. It is a perspective view which shows other embodiment which piled up several pressure sensitive sensor means in the row direction and the column direction. It is a functional block diagram which shows one Embodiment of the body movement detection apparatus which has a biting volume detection means. It is a functional block diagram which shows one Embodiment of the body movement detection apparatus which has a contact area detection means. It is a functional block diagram which shows one Embodiment of the resistance detection means which has a resistance value correction means. It is the perspective view and equivalent circuit which show the structural example of a lead wire, resistance, a capacitor | condenser, and a coil using a conductive elastomer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Pressure sensor means 101-104 Pressure sensitive sensor means 101a Electrode attaching part 101b Electrode 200 Pressure detection means 201 Resistance detection means 202 Resistance / pressure conversion means 300 Pressure distribution calculation means

Claims (5)

In the body motion detection device that detects the movement of each part of the subject's body at bedtime,
Pressure sensor means arranged on the bedding of the subject and having at least one conductive elastomer sheet whose resistance changes depending on the pressure received in a region of a predetermined shape as a pressure sensor;
Resistance detection means for detecting a change in resistance of the conductive elastomer sheet by converting it into a voltage or current; and
Resistance / pressure converting means for converting the detected resistance into pressure;
Pressure distribution calculating means for calculating a pressure distribution from the converted pressure value;
A body motion detection device comprising:   The pressure sensor means is divided into a plurality of conductive elastomer sheets having a predetermined shape with a predetermined interval, and all or part of one surface of two adjacent conductive elastomer sheets is highly conductive. Connect with an elastomer sheet or conductor, and for the next adjacent conductive elastomer sheet, connect all or part of the opposite surface to the previous conductive elastomer sheet with a highly conductive elastomer sheet or conductor. The body motion detecting device according to claim 1, further comprising a structure in which all the conductive elastomer sheets are connected by alternately changing the side of the connection surface with the adjacent conductive elastomer sheet.   In the conductive elastomer sheet, at least one branch input / output terminal is formed midway between the input / output terminals at both ends, and the resistance value between one or both of the branch input / output terminals and the input / output terminals at both ends is small. The body motion detection device according to claim 1, wherein the body motion detection device is detected.   A pressure sensor means comprising a plurality of pressure sensitive sensor means arranged in the same direction and a plurality of pressure sensitive sensor means arranged in a direction orthogonal to the line. Item 4. The body motion detection device according to any one of Items 1 to 3.   2. A resistance value correcting unit that corrects a change in resistance value due to compression set, reduction in impact resilience, or deterioration of the conductive elastomer according to a compression history or a resistance value fluctuation history. The body motion detection device according to any one of 1 to 4.

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